1. Field of the Invention
The present invention relates to a novel four-step method for synthesizing styrene by employing toluene as the starting material. More particularly, it pertains to a new method of making styrene at a markedly reduced cost by: (a) oxidizing toluene to obtain predominantly benzyl acetate; (b) carbonylating said benzyl acetate with a gaseous mixture containing carbon monoxide to form phenylacetic acid; (c) hydrogenating said phenylacetic acid to form phenyl ethanol; and (4) dehydrating said phenyl ethanol to produce styrene.
2. Description of the Prior Art
The art is replete with various processes for the production of styrene, see, e.g., Y. C. Yew and T. H. Vanden Bosch, STYRENE (Supplement A; 1973). However, these various methods have centered around the basic concept of dehydrogenating ethyl benzene to form styrene as follows: ##STR1##
A variety of materials has been tried as starting materials in order to obtain ethyl benzene at a lower cost, which is used as the reactant in the conventional process described in Equation 1. Representative of them include benzene and its alkyl derivatives, toluene, vinylcyclohexene, ethyltoluene and 1,1-dimethylcyclohexane. None of the chemicals listed above, except benzene, has proven to be commercially feasable due to poor conversion rates and low yields. In view of the above, benzene and ethylene have been most commonly used to first prepare ethyl benzene and then manufacture styrene as follows: EQU C.sub.6 H.sub.6 +CH.sub.2 .dbd.CH.sub.2 .fwdarw.C.sub.6 H.sub.5 CH.sub.2 CH.sub.3 .fwdarw.C.sub.6 H.sub.5 CH.dbd.CH.sub.2 +H.sub.2 (Eq. 2)
During the last decade or so, however, benzene and ethylene have experienced dramatic price increases. Accordingly, in view of the above, the need has existed for an effective commercial process for manufacturing styrene, which commands itself to a wide variety of commercial uses such as the manufacture of synthetic rubbers and various styrene-based plastics, at a lower manufacturing cost than conventional techniques known to the art.